with Glenn Lym. It is a common assumption that street grids were imposed easily on San Franciscoâs original landscape, resulting in the cityâs photogenic hillside streets that poke up from otherwise large flat planes. We assume that the imposition of these grids was benign. But it was not benign. Digging under the streets of early San Francisco, we will find that much of San Franciscoâs flatland was created from land forms that were quite different from what we know today.